Hannah Upp had been missing for nearly two weeks when she was seen at the Apple Store in midtown Manhattan. Her friends, most of them her former classmates from Bryn Mawr, had posted a thousand flyers about her disappearance on signposts and at subway stations and bus stops. It was September, 2008, and Hannah, a middle-school teacher at Thurgood Marshall Academy, a public school in Harlem, hadn’t shown up for the first day of school. Her roommate had found her wallet, passport, MetroCard, and cell phone in her purse, on the floor of her bedroom. The News reported, “Teacher, 23, Disappears Into Thin Air.”

A detective asked Hannah’s mother, Barbara Bellus, to come to the Thirtieth Precinct, in Harlem, to view the Apple Store surveillance footage. Barbara watched a woman wearing a sports bra and running shorts, her brown hair pulled into a high ponytail, ascend the staircase in the store. A man stopped her and asked if she was the missing teacher in the news. Barbara said, “I could see her blow off what he was saying, and I knew instantly it was her—it was all her. She has this characteristic gesture. It’s, like, ‘Oh, no, no, don’t you worry. You know me, I’m fine.’ ” Another camera had captured Hannah using one of the store’s laptops to log in to her Gmail account. She looked at the screen for a second before walking away.

The sighting was celebrated by Hannah’s friends, many of whom were camping out at her apartment. They made maps of the city’s parks, splitting them into quadrants, and sent groups to look in the woods and on running paths and under benches.

According to the Myers-Briggs personality test, which Hannah often referenced, she was an E.N.F.P.: Extraverted Intuitive Feeling Perceiving, a personality type that describes exuberant idealists looking for deeper meaning and connection. Five of her friends used the same phrase when describing her: “She lights up the room.” A friend told the News reporter, “Everyone you talk to is going to say she is their closest friend. She has no barriers. She was raised to trust and care for everyone, and she did.”

Two days after Hannah was seen at the Apple Store, she was spotted at a Starbucks in SoHo. By the time the police arrived, she had walked out the back door. The police recorded sightings of her at five New York Sports Clubs, all of them near midtown, where the detective on the case presumed she had gone to shower. In an article about her disappearance, the Times wrote, “It was as if the city had simply opened wide and swallowed her whole.”

On September 16th, the twentieth day she’d been missing, the captain of a Staten Island ferry saw a woman’s body bobbing in the water near Robbins Reef, a rocky outcropping with a lighthouse south of the Statue of Liberty. Two deckhands steered a rescue boat toward the body, which was floating face down. “I honestly thought she was dead,” one of the men said. A deckhand lifted her ankles, and the other picked up her shoulders. She took a gasp of air and began crying.

The woman was taken to Richmond University Medical Center, on Staten Island. For three weeks, her own biography had been inaccessible to her, but when the medical staff asked her questions she was suddenly able to tell them that her name was Hannah and to give them her mother’s phone number. Barbara arrived within an hour. (Hannah’s father was living in India, where he taught at a seminary; her brother, a Navy officer, was stationed in Japan.) Barbara said that Hannah looked “both sunburned and pale, like she’d been pulled behind a boat for three weeks.” The first thing she said was “Why am I wet?”

She was treated for hypothermia, dehydration, and a severe sunburn on the left side of her body, and her condition rapidly improved. Four friends came to the hospital that afternoon. Manuel Ramirez, her roommate, said, “She saw me and smiled and said something like ‘I hope they release me soon, because I have to set up my classroom.’ She clearly didn’t get that three weeks had passed.”

Later that day, the police interviewed Hannah privately. Barbara stood outside the room. “I could hear her trying to respond to their questions—she was really working at it, trying to give them what they wanted—but she didn’t have any explanation.” Her last memory was of taking a run in Riverside Park, near her apartment, the day that she went missing.

Barbara, a United Methodist pastor, slept in a chair beside Hannah’s hospital bed. In the middle of the night, Hannah jolted awake. “I was at a lighthouse,” she said, then immediately fell asleep again. In the morning, when Barbara asked about the lighthouse, Hannah said that she had no memory of it.

Hannah was transferred to a psychiatric unit run by Columbia University Medical Center. She underwent a series of brain-imaging tests, but the doctors couldn’t find any neurological condition that would cause her to forget her identity. They concluded that the episode was psychological in nature. As soon as she was lifted from the river, she remembered all the details of her life prior to her disappearance.

She was given a diagnosis of dissociative fugue, a rare condition in which people lose access to their autobiographical memory and personal identity, occasionally adopting a new one, and may abruptly embark on a long journey. The state is typically triggered by trauma—often sexual or physical abuse, a combat experience, or exposure to a natural disaster—or by an unbearable internal conflict. Philippe Tissié, one of the first psychiatrists to study fugue, characterized it as a kind of self-exile. In 1901, he wrote, “The legend of the Wandering Jew has become a reality, proved by numerous observations of patients or unbalanced persons who suffer from an imperious need to walk, on and on.”

Hannah was hypnotized, to see if she could recall a traumatic event that triggered her fugue, but she couldn’t remember anything unusual. Hannah and her mother, father, and brother said that as a young child she hadn’t endured anything that they considered trauma. Hannah’s roommate, Ramirez, said that, when he visited her on the psychiatric unit, “she was her normal, upbeat, funny self. I remember her rattling off all these possibilities: ‘Was I in a hit-and-run? Was I mugged? Was I assaulted?’ ” The beginning of the school year was always stressful—her students struggled with problems, such as hunger and unstable housing, that she couldn’t address within the confines of her classroom—but her colleagues had the same dilemmas.

In the hospital, Hannah read the news articles about her disappearance and the comments from readers, some of whom accused her of staging it. She was so embarrassed that she contemplated changing her name. But, her friend Piyali Bhattacharya said, “she ultimately decided—and she was very clear on this—that she did not want to run away from who Hannah Upp was.”

One of the psychiatrists on Columbia’s psychiatric unit, Aaron Krasner, now a professor of clinical psychiatry at Yale, described the comments in the news as “very condemning and discrediting. I think this speaks to the rage that dissociative conditions incur in certain people. There is an ineffable quality to dissociative cases. They challenge a conventional understanding of reality.” He told me that he was troubled by the narrowness of medical literature on these states; there are no medications that specifically target the problem. “Dissociative fugue is the rare bird of dissociation, but dissociation as a phenomenon is very common,” he said. “I think as a field we have not done our due diligence, in part because the phenomenon is so frightening. It’s terrifying to think that we are all vulnerable to a lapse in selfhood.”

Freud explored dissociative states in his early writings, but the phenomenon did not fit easily into his sweeping theory of human behavior. Most of the dissociative patients he saw said that they had been sexually abused as children, but he ultimately concluded that their memories were fantasies. He proposed that unacceptable wishes were repressed into the unconscious, and that traces of them resurfaced in people’s fantasy lives. Theorists of dissociation disagreed, arguing that some events were so traumatic that, afterward, the mind was unable to develop as an integrated whole. The French philosopher and psychologist Pierre Janet, who developed the first formal theory of dissociation, in 1889, wrote, “Personal unity, identity, and initiative are not primitive characteristics of psychological life. They are incomplete results acquired with difficulty after long work, and they remain very fragile.” After Freud’s success, Janet’s work fell into obscurity.

Cases of dissociation had a whiff of the mystical, and doctors tended to stay away from them. Dozens of articles from the turn of the twentieth century, published in the Times, recount miraculous, inexplicable transformations: a Minnesota reverend, missing for a month, realized that he had travelled across the county and enlisted in the Navy, “though never before in his life had he even gazed on the ocean”; a professor thought to have drowned was discovered, three years later, using a new name and working as a dishwasher; a deacon in New Jersey woke up and “realized the room he has occupied for more than a year was strange to him” and his Bible was marked with someone else’s name. He had been missing for four years.

The most famous American fugue patient was Ansel Bourne, a preacher who, in 1887, left his home in Rhode Island with a vague sense that he had fallen from “the path of duty.” He travelled to Norristown, Pennsylvania, two hundred and forty miles away, and opened a shop selling stationery and candy. He went by the name Albert Brown. His neighbors found his behavior perfectly normal. Two months after leaving home, he knocked on his landlord’s door and asked, “Where am I?”

The philosopher and psychologist William James offered to treat him by using hypnosis to “run the two personalities into one, and make the memories continuous.” But the two identities could not be merged. Bourne returned to his wife in Rhode Island with almost no memories of his life as Albert. In an essay that James wrote shortly before treating Bourne, he argued that science would advance more rapidly if more attention were devoted to unclassifiable cases—“wild facts” that threaten a “closed and completed system of truth.” Understanding splits in consciousness, he wrote, is “of the most urgent importance for the comprehension of our nature.”

But, in the decades after Bourne’s disappearance, the study of dissociation largely vanished. The prevailing schools in psychology and psychiatry—behaviorism and psychoanalysis—adopted models of the mind that were incompatible with the concept. Then, in the nineteen-eighties, several thousand people claimed that, having been abused as children, they had developed multiple selves. The public responded to these stories much as it had to the surge of dissociative cases at the turn of the century: this sort of mental experience was considered too eerie and counterintuitive to believe. Whatever truth there was to the condition was lost as hyperbolic stories circulated in the media: tales of feuding selves and elaborate acts of sexual abuse, such as torture by satanic cults. The legacy of that time is that people with similarly radical alterations of self are viewed with distrust.

Richard Loewenstein, the medical director of the Trauma Disorders Program at Sheppard Pratt, in Towson, Maryland, may have worked with more fugue patients than any other psychiatrist in the country. He said that modern psychiatry and psychology still fail to “pay much attention to the self or to the complexities of subjectivity.” When he encounters people in fugues, often in emergency rooms, he finds it nearly impossible to treat them in that state. He said that, in conversation, “there’s a quality of them running away from whatever you are trying to ask them. If you begin to hold on to them and try to get them to stay in one place, they go—they’re gone.”

The first time I spoke with Hannah’s mother, early this year, she told me it was important that an article about her daughter’s experience “let it stay a mystery.” She felt that Hannah’s condition lay at the “edges of knowledge,” and she didn’t want to impose false connections. The more she read about fugue, the less she felt she understood it. Hannah’s father, David Upp, wrote in an e-mail, “I suspect they will need a new paradigm, before Fugues can fit ANY theories.” He suggested that “magical realism comes closer” than any current psychological theory, and said that one of Hannah’s favorite authors is Isabel Allende. “Perhaps a book like ‘El Plan Infinito’?” he wrote. The book’s hero spends decades wrestling with the teachings of his father, who, like Upp, became an itinerant preacher.

As a child, Hannah was “the princess of her church,” as a friend described her. She grew up in Japanese-American churches in Oregon, where her parents served as pastors. (Both of her parents are American, but Barbara taught in Japan and is fluent in Japanese.) When she was young, her parents’ perspectives on theology sharply diverged. Upp characterized himself with the phrase homo unius libri, “man of the one book.” In monthly newsletters sent to colleagues, congregants, and friends, he argued that “there is no such human as a natural homosexual.” He urged his readers to “fully support Biblical Morality and to oppose any compromise with sexual deviance/perversion.”

Barbara filed for divorce when Hannah was fifteen. Upp moved abroad and taught the Gospel, often to indigenous tribes, in Fiji, Palau, Guam, Malta, India, Zimbabwe, Guyana, and the Philippines, where he now lives in a one-room house in a remote village. In 2007, Barbara took a leave from her position as a pastor and moved to Pendle Hill, a Quaker retreat outside Philadelphia. She and Upp stopped speaking to each other.

Hannah was a creationist when she arrived at Bryn Mawr, and she joined the InterVarsity Christian Fellowship, an evangelical campus ministry. Her friend Piyali Bhattacharya, who was raised Hindu, once asked Hannah, “Do you think I’m going to Hell?” She said that Hannah began crying. “Hannah lost it. She couldn’t answer the question. Whereas another person might try to defend her beliefs, Hannah is the kind of person who would take a question like that and turn it in on herself and think about it and come out the other end being a different person.” Bhattacharya went on, “She knew she was loving and openhearted, but beyond that I think she had zero idea of who she actually was. She wanted to give herself over to someone or some idea.”

In the spring of her sophomore year, Barbara said, Hannah called her, crying, after going to a talk by Beth Stroud, a United Methodist minister who was defrocked after telling her congregation that she was in a relationship with a woman. “Hannah was troubled that something that she’d thought was part of her faith was cruel,” Barbara said. By her junior year, Hannah was dating a woman.

Although she found herself drawn to Quakerism, she still travelled with her father at least once a year in whatever part of the world he was teaching. Her friend Hannah Wood wondered what it meant for Hannah to “swallow a part of herself down while she was travelling,” but Hannah always spoke fondly of her father. Her friends liked to joke that she resided in “Hannah Land.” Her friend Amy Scott said, “She lives in this separate place where there are butterflies and birds, and they follow her around. Everything is good and everyone is happy, and there’s no conflict, ever.”

Hannah thought that her fugue may have begun with a liminal phase: there were two days when she slept in her apartment but communicated with no one. Her bank records showed that she had gone to a movie in Times Square which she had no memory of seeing.

During the weeks that Hannah spent wandering, her family believes that she understood on some level that people were searching for her. “She characterized her recollections of that time as just being continually roaming,” her brother Dan said. “We think that maybe she had this sense that she was being hunted and didn’t know why.”

A few months before her disappearance, Hannah and a friend had gone to a meeting for “freegans,” a group that tries to minimize its consumption of resources, and they’d visited grocery stores on the Upper East Side, collecting discarded food. Dan said that the family believed Hannah “remembered what she’d learned on the tour and was eating perfectly good food that the stores were not able to legally sell the next day. She seemed to have access to those memories. Even if she didn’t understand why at that time, she gravitated to places that were familiar.”

Dan met with the captain of the Staten Island ferry and analyzed the currents in the Hudson River. They surmised that Hannah must have entered the river in lower Manhattan before the tide took her south. Hannah and Dan walked along the piers downtown, and when they got to Pier 40, a former marine terminal on the west end of Houston Street, Hannah told him that the place felt familiar. She remembered lights floating on the water.

Dan learned that there had been a Japanese floating-lantern ceremony on the pier on September 11th, to honor the victims of the World Trade Center attacks. As a child, Hannah had danced in an annual Obon festival, which has a floating-lantern ceremony, the lights representing the souls of the departed. Barbara said, “Something about that powerful ritual registered.”

Hannah Upp visiting Maria Montessori’s grave site. In 2014, Hannah took a job at a Montessori school in St. Thomas. After Hurricane Irma hit, she told a friend, “I’m staying—that’s where my heart is.”

Photograph courtesy Barbara Bellus

Based on the condition of her body the day she was found, she and her family concluded that she had been at the floating-lantern ceremony and, three days later, had returned to the pier and entered the water. Barbara said, “Maybe when Hannah was getting alarmed or upset because people kept saying her name, it felt more comfortable to go back to that place.”

It is likely that Hannah spent the night in the river. She later checked the lunar calendar and was able to confirm her memory that there had been a full moon that night. Her skin showed signs of prolonged immersion. Barbara said that Hannah vaguely remembered “holding on to the hull of a barge—she may have wanted some rest—and then she realized that she was being sucked toward the propeller, which is a very dangerous thing, so she swam away.” It was as if her body, undirected by what we typically conceive of as consciousness, were still intent on survival.

Hannah and her family concluded that she either swam to or was washed up onto Robbins Reef. She scraped her knees on its rocks. She slept there the following day, long enough to get a sunburn. Then she returned to the water.

Bhattacharya said that when she and Hannah spoke about the experience they often lapsed into silence. “It felt like the words we have in the English language were not sufficient to describe this,” Bhattacharya said. Hannah saw a few therapists, but found conversations with her friends more helpful. She described the mental-health system as dogmatic and overly attached to its diagnostic models. She felt as if her experiences had to be reshaped to fit within the diagnoses. Barbara said that Hannah told her, “If people want to spend a lot more time figuring out what set this off, they can, but I’m not going to spend the rest of my life focussing on it.” Barbara found the same tendencies within psychiatry as she had in the church: an emphasis on what she described as “the letter of the law, rather than the spirit of it.” She didn’t think it “left room for the reality of individual unique experience.”

Hannah’s fugue seemed to fit what Etzel Cardeña, a professor of psychology at Lund University, in Sweden, describes as “anomalous psychological experience.” Cardeña has published a textbook on phenomena that “fall between the cracks of the house built by contemporary mainstream psychology.” He told me, “In our culture, we have a nice narrative that personality is stable. That is a fiction. When a person enters a fugue and becomes someone else—or isn’t there—it’s an exaggerated version of the way we all are.”

Cardeña has done research on altered states of consciousness in religious practice, and he found that some people who would otherwise be given a diagnosis of dissociative disorder have been able to channel their tendencies into rituals of spirit possession, trance, speaking in tongues, or intimate experiences of God. He said, “There is a cultural context for surrendering themselves. It’s not about getting rid of the dissociative state so much as giving it a syntax, a coherence, a social function.” In an article in the journal Spiritus, T. M. Luhrmann, a Stanford anthropologist who studies religion and psychiatry, suggests that there is a “shared psychological mechanism” in dissociation and evangelical worship: the capacity to withdraw from the everyday and become entirely absorbed by interior experience. “Trance-like responses to great distress have occurred throughout history and across culture,” she writes.

Nearly all the medical literature suggests that people in fugue states adopt new identities, but Barbara said that, for Hannah, “it was more like the complete absence of identity,” a kind of “dangerous nothingness.” None of Hannah’s friends or family had ever seen her in a fugue state, beyond the surveillance footage from the Apple Store. Barbara said, “Nothing we know indicates that she built a new identity—unless she did and it was lost when she came back.”

David Spiegel, a professor of psychiatry at Stanford who has spent his career studying dissociation, told me that he’d never heard of someone navigating the world without something that resembles an identity. “It may be sparse, with far less structure or detail to it, but I don’t know if you can be a functioning human without something that passes for a self,” he said. “You need some kind of orientation for understanding who you are and what you are doing here.”

A little more than a year after her disappearance, Hannah left New York, joining Barbara at Pendle Hill. Sometimes called Mecca for Quakers, the institution was founded in 1930 as a retreat for people of all religions. Hannah worked in the kitchen and attended daily meetings for worship, a half hour of silence.

Quaker practice operates according to the premise that a single person cannot see the entire truth, and the people at Pendle Hill never asked Hannah for answers about her disappearance. Patrick Roesle, an intern at Pendle Hill whom Hannah dated there, said that he viewed the episode as a “freak accident.” He believed that “Hannah gives so much to other people that at a certain point there is literally nothing left, and she departs from herself.” When friends had celebratory occasions or setbacks, however minor, she would write them cards by hand. To a friend at Pendle Hill who broke an arm, she wrote, “It’s an honor to fold your laundry or crawl under your bed, for, you see, that’s what community is all about!” Her friend Hannah Herklotz said that Hannah was so attentive to other people’s needs that it sometimes felt impossible to reciprocate. “You’d come out of a two-hour conversation that you’d feel was incredibly deep, and you’d feel heard and known and seen, and then you’d realize later: she didn’t tell me a thing about herself.”

After working at Pendle Hill for three years, Hannah was hired as a teaching assistant at a Montessori school for underserved children in Kensington, Maryland. She was drawn to Maria Montessori’s notion of an “education capable of saving humanity”: by protecting the autonomy of children, society would become more loving, peaceful, and unified. Roesle said, “She flung herself—all of her weight—into learning Montessori, internalizing Montessori, loving Montessori.”

On the morning of Hannah’s first day of class, Barbara got a phone call from the police. They told her that Hannah’s purse, wallet, and cell phone had been found on a wooded footpath in Kensington. A colleague reported that as she was driving to school she had seen Hannah walking quickly in the wrong direction. Hannah’s mother and friends from Pendle Hill drove to Maryland and looked for her in the woods and put up flyers around town. They discovered that she hadn’t slept at her apartment the night before. In the previous twenty-four hours, no one had talked to her.

The next day, at 10:30 P.M., Barbara received a call from an unknown number. “All she said was ‘Mom?’ ” Barbara said. Hannah had found herself in a dirty creek in a residential area in Wheaton, Maryland, a mile and a half from her school. There was a shopping cart beside her. Barbara’s housemate at the time, Jennifer Beer, recalled that Hannah “regathered herself instantly—it was sort of like her soul getting sucked back in.” Hannah walked to the closest commercial area and borrowed a stranger’s phone. She realized that she had been walking for more than two days.

Later, Hannah reviewed the text messages she’d sent the day that she disappeared. “We could see in the texts where she had made that transition,” Barbara said. “She could remember sending some of the texts, but then there came a point where she said, ‘I don’t remember writing any of this.’ ”

Barbara said that after each fugue she felt a kind of “awe at where Hannah had been.” The ancient Greeks had two words for time: kronos, chronological time, and kairos, which is often translated as “the right time” and cannot be measured. Barbara said, “I imagined her as having entered more fully into kairos—the appointed time, the fullness of time. There’s a suspension of certainty.”

Hannah’s friends were struck by the similarities between her two disappearances. In both instances, she had disappeared at the beginning of the school year, after travelling with her father. David Upp had pondered whether the vacations had been a trigger for her, but he wasn’t satisfied with that explanation. “Travel? That’s just ‘what we do,’ ” he wrote me. “Hannah and I have been to twenty-five nations together, so it is ‘normal’ not disruptive.” In an article for Bryn Mawr Now, a campus newsletter, Hannah had once described the “violent surprise” and loneliness of returning home from a trip to Ghana. “I thought I was coming ‘home,’ but was surprised at the longing for a new place that had grown so comfortable,” she wrote.

In both fugues, she had been drawn to water. Her friend Amy Scott said, “The way she describes it is she finds herself in a body of water and realizes who she is.”

Hannah returned to her job within a few days. The following year, she was hired as a teaching assistant for preschoolers at a Montessori school in St. Thomas, in the U.S. Virgin Islands. When she disclosed her condition, the administrators at the school were warm and accepting. She joked with friends that she was moving to paradise.

After the Maryland disappearance, Barbara said that friends asked her, “Couldn’t you put a chip in her, like you would in a schnauzer?” The police in Maryland had proposed using the type of ankle bracelet designed for people who are under house arrest. “She didn’t want to pursue it—she refused to be defined by this—and I chose to honor her decision,” Barbara said. “I had to be clear that I’m not living my daughter’s life—she’s living it, and she needed to have the freedom to make choices.”

Hannah moved to the east end of St. Thomas, away from the docks for cruise ships, which bring tens of thousands of tourists to the island every week. She could see the British Virgin Islands from the balcony of her apartment, which she called her “island palace.” A parent of one of her students described her as a “modern-day Mary Poppins.” The head of the school, Michael Bornn, said, “Whenever a parent showed up for a tour, we took them to Hannah’s classroom.”

After a year of teaching, the school paid for her to take summer classes at a Montessori training center in Portland, Oregon, so that she could eventually become certified and lead her own class. One of the school’s directors, Norma Bolinger, said, “She totally absorbed the Montessori theory, to the point where I could see her becoming a mover and shaker in politics and trying to get Montessori into all schools globally.” Hannah made a pilgrimage to Maria Montessori’s grave, on the Dutch coast. Bhattacharya said, “It was Hannah’s new church. There’s a book; there are rules. If you follow the rules, good things happen to good people. Her desire to worship never left her.”

In St. Thomas, she attended a few meetings devoted to the Bahá’í faith, a Persian religion that teaches the unity and equality of all people, but she was put off by what she saw as the community’s negative judgment of nontraditional families. She saw a therapist on the island, but she put more stock in tending to her physical health. She swam in the ocean nearly every day, becoming so strong that she could reach cays more than two miles away. “She found the world underwater just so peaceful and so magical,” Scott said. “Her solace was always the majesty of the island.”

Hurricane Irma hit St. Thomas on September 6, 2017, a week after Hannah began her fourth year of teaching. That summer, she had completed her Montessori degree. She and her roommates huddled in the laundry room of their apartment. The wind reached a hundred and eighty-five miles an hour, shattering one of their windows. With each new gust, a power line, dislodged by the storm, smacked the roof.

The next morning, the island had turned brown, the trees stripped of their leaves. Suzanne Carlson, a reporter at the Virgin Islands Daily News, told me, “I heard a lot of people say, ‘This is it—St. Thomas is over.’ ” Hannah texted friends that she was safe but the island was devastated. “I don’t recognize anything,” she wrote.

Since her 2008 fugue, Hannah’s roommate from New York, Manuel Ramirez, had used a code phrase to check up on her. After her first disappearance, they had made fun of an ABC News story that characterized her as a “friendly vegetarian who constantly experimented with new dishes.” After the storm, Ramirez texted her “friendly vegetarian.” Hannah wrote back, “I like to try new dishes.”

Six days after the storm, Hannah drove to the house of an ex-boyfriend, Joe Spallino, a scuba instructor, and saw that his belongings were gone. Hannah learned from his landlord that he had rushed to the marina to get on one of the “mercy ships” giving people free rides off the island. Hurricane Maria, another Category 5 storm, was forecast to hit the island the following week.

Hannah drove to the marina to say goodbye. Spallino was waiting to board a cruise ship to Puerto Rico, and they talked for several hours. Spallino said, “I kind of jokingly asked, ‘What if you come along?’ She thought about it and said that, in reality, she wouldn’t want to.”

After Hannah left the marina, she never used her phone again. The next day, she helped Norma Bolinger prepare the school for Hurricane Maria by taking pictures off the walls. Bolinger said, “She responded to everything I asked with ‘Yes, Norma.’ ‘Yes, Norma.’ ‘Yes, Norma.’ Which normally wasn’t her tone of voice to me. Hannah was not a ‘yes’ sort of person. If you asked her to do something, she would want to know why.”

That night, Hannah’s three roommates told her that they were all trying to leave the island. One of them, Leslie Bunnell, said that Hannah told her, “I’m staying—that’s where my heart is. School is going to be the first step toward normality for these kids.” The next morning, Hannah said that she was heading to school, and a roommate watched her get in her car. She never showed up at the school. The following day, there was a faculty meeting, and she wasn’t there. Her friend Maggie Guzman called Hannah’s closest friends, on the island and in the States, but no one had spoken to her for three days. It was the same time of year as her previous two fugues, and they told Guzman to search near the water.

Guzman and other friends started with Hannah’s favorite beach, Sapphire, where she often snorkeled. Near the water, there was a small bar that served hamburgers and mimosas. On a stool, they found Hannah’s sundress, her sandals, and her car keys. Workers said that they had discovered the belongings in the sand when they were clearing debris from the storm. Hannah’s car was in the parking lot. Inside were her purse, wallet, passport, and cell phone.

Given Hannah’s strength as a swimmer, her friends assumed that she could survive for several days in the water. By boat, they searched the shoreline and a small island nearby, where the current might have taken her. The Coast Guard sent three helicopters. Her friends also checked the manifests of people evacuated on mercy ships, but her name wasn’t listed. The storm had exacerbated deep divisions on the island—some people could leave, while others had no means to travel and nowhere to go—and Hannah’s family and friends felt self-conscious about the fact that they were searching “for one white gal in a sea of troubles and suffering,” as one put it.

After three days, they had to call off the search to prepare for Hurricane Maria, which brought heavy rain to the island. When the storm subsided, an E.M.T. named Jacob Bradley, who had set up a makeshift emergency-medical-services station on the island, organized another search. If Hannah had drowned, her body would likely float to the surface within a few days. Bradley circled the island and all its cays in a rescue boat and also canvassed the airport, the homeless shelters, the beaches, and the hospitals, and interviewed captains who came in and out of the island’s marinas. He went to the morgue and looked at ten unclaimed bodies. None of them were Hannah.

Hannah’s friends developed a range of theories for what had happened, all of which they acknowledged were unlikely. But her survival in New York had been improbable, too. One friend from St. Thomas said, “There are pockets of communities in the bush, and she could be living there.” Others thought that Hannah, who is fluent in Spanish, might have got on a boat to Puerto Rico or St. Croix or Miami without I.D. and integrated into a community of displaced people. “Even if she doesn’t have a grip on her past, she’s still Hannah, and she’s probably doing what she can to be of service to the people around her,” Roesle, her ex-boyfriend, said. Hannah Wood said, “Even if she’s not aware that she’s herself, she’s a very charming person. If someone was inclined to do a good deed, she’d be the kind of person who would persuade someone to do it.”

After her first fugue, Hannah gave her mother “Traveling with Pomegranates: A Mother-Daughter Story,” a memoir framed as a modern version of the myth of Persephone and Demeter. Hannah rarely spoke about her fugue, but Barbara was touched by what she felt was an allusion to the experience. Demeter searches the earth for her daughter, Persephone, who has been taken into the underworld. “I remember reading that Persephone falls into an abyss, and that just hit something close to my heart,” Barbara said. Even when Persephone is saved, Hades requires that she return to the underworld for a portion of each year. With each fugue, Barbara found more solace in what she described as “the primal archetype of the daughter descending and the mother seeking her, whatever that takes.”

After Bradley’s search failed to turn up any bodies, Barbara’s clearness committee, a group of Quakers appointed to guide someone facing a dilemma, bought her a one-way ticket to St. Thomas. She asked the Red Cross if she could do volunteer work in exchange for a bed. “I didn’t want to take up precious resources,” she said. The Red Cross put her in touch with the owner of the Windward Passage Hotel, in downtown St. Thomas, which was providing rooms to recovery workers and hotel employees who had lost their homes in the storms.

Barbara arrived on the island on November 21st, more than two months after Hannah disappeared. Her room looked out on the part of the harbor where seaplanes take off. The cruise ships had begun to return, and the businesses devoted to their passengers—on a street behind the hotel were Dynasty Dazzlers, Ballerina Jewelers, Jewels Forever, and a dozen other jewelry stores—were reopening.

Barbara is constitutionally optimistic, and she tried to cast away the idea of negative outcomes. She drove Hannah’s car—a black Suzuki, whose back window had been blown out by Hurricane Irma—and went to Hannah’s favorite beaches, restaurants, and shops. “I do have the sense sometimes that she’s around any corner,” Barbara told me. She talked to Hannah’s friends and colleagues, trying to understand her last known interactions. Barbara believed that this fugue, too, may have started with a prelude in which Hannah was still home and communicating with people in a rudimentary way, without encoding the interactions into memory.

Barbara called Richard Loewenstein, the psychiatrist who specializes in fugues, and was struck by his conviction that dissociative fugues are organized and purposeful, operating according to some internal logic. The person’s thinking is dominated by a “single idea that symbolizes or condenses (or both) several important ideas and emotions,” Loewenstein writes.

Barbara tried to imagine what thought could be motivating her daughter to journey to water. She contemplated the symbolism of baptism. “One rises from the water reborn,” she said. But, in the United Methodist tradition in which Hannah was raised, believers are not required to be fully immersed. Barbara also considered the imagery of creation in the Old Testament. “The water is a vast chaos, formless—a void,” she said. “Could it be a kind of metaphor for the primeval chaos out of which creation comes?” The description in Genesis reads, “Now the earth was formless and empty, darkness was over the surface of the deep, and the spirit of God was hovering over the waters.” But, Barbara added, “we don’t generally get so literal about it as to charge off into the briny deep or the creek.”

She said that, one day, shortly before she filed for divorce, she, too, had entered a kind of dissociative state, in part, she believes, in response to a medication that she had just started taking. She had been on her way to teach a class, at a United Methodist church, about the women who worshipped at the church at Corinth. The women’s existence is recorded only because Paul admonished them for preaching and prophesying in public. “The husband is the head of his wife,” he wrote.

The last thing Barbara remembered was driving south on the highway. She found herself beside the Willamette River. “Why did I go to the water?” she asked. “I do remember feeling comfort finding myself there.” She sat in her car for several hours. “I had lost the ability to understand categories,” she said. “I no longer had a chronological measure of time. I no longer experienced myself in a specific place. I didn’t have an understanding of the mechanisms by which this world fits together.” After several hours, she drove home. She said, “I fully came to when I saw my children’s faces, and I thought, Oh, my God—they’re worried.”

The front-desk manager of the Windward Passage Hotel, Vedora Small, is a middle-aged mother from St. Thomas whose home was destroyed in the storm and who lives in a room on the same floor of the hotel as Barbara. She often lies in bed at night wondering where Hannah could be. “I know St. Thomas is a small place and it looks simple,” Small told me. “But you can live here for years and I don’t see you and you don’t see me.”

Small took Barbara to shelters and abandoned buildings where people who are homeless or mentally disturbed often turn up. On the island, there are only thirty-two beds for psychiatric patients—the shortage is so severe that a judge recently ordered a mentally ill man to live in his pickup truck—and a large number of people are chronically adrift. After the storms, more people joined their ranks. Barbara was repeatedly directed to the same circuit of buildings: a night club downtown that had been the site of several crimes, a car wash on a side street near Frenchtown, and a house where people from the car wash always told her to go. It was owned by a man who was rarely home. Under his door, Barbara slipped a flyer with Hannah’s face on it that warned she “may not know who she is.”

When I visited these sites with Barbara, people who were drunk, high, or unhinged seemed to engage with reality for long enough to tell her that they were praying for her. One woman, who was struggling to stay upright, told Barbara, “I love you, you will find her—even if she’s dead, you’re still going to find her.” A woman who worked at a farm on the Estate Bordeaux, a former sugar plantation, said that she understood why someone might forget her identity during the storm. “There was a lot of trauma,” she said softly. “It cracked things wide open.” A man making hamburgers at the bar at Sapphire told Barbara that a few people had drowned near the beach in the past. “I don’t think she went out into the water,” he said. “Everything that goes out comes back this way. She would have washed up already.”

Every few weeks, there was another sighting. It was often the same women: a white teacher at a different private school on the island, or an older, homeless woman from Massachusetts who panhandled in an open-air mall near the marina.

On January 23rd, two caseworkers at the Bethlehem House Shelter for the Homeless, in downtown St. Thomas, reported that they had just seen Hannah at an abandoned building where people often smoked crack. Barbara and a detective from the Virgin Islands Police Department, Albion George, drove to a peach-colored, crumbling three-story structure close to Market Square, a produce market that was once the site of some of the largest slave auctions in the world. They climbed a steep flight of concrete steps with no railings. Detective George reached the third floor and saw the woman. “I thought, My God, that’s her,” he told me. “My heart was beating. I grabbed her right away and handcuffed her.”

The woman was thin and had acne, and her light-brown hair was in a bun. Her eyes were a striking sea green. Barbara reached the top of the stairs a minute later, and told George that it was not Hannah. The woman was shouting about police accountability—she said that she needed George’s badge number. George went to release the handcuffs, and Barbara touched the woman’s shoulder and apologized over and over. She explained that she was searching for her daughter. The woman had seen the flyers for Hannah. She told Barbara, “I wish I were her for you.”

An emergency call came over George’s radio, but Barbara was reluctant to leave. She was moved by the woman’s compassion and wondered if her mother was looking for her, too. After she returned to the hotel, she wished she could go back and help the woman somehow. She realized that in the time it had taken to drive to the building and climb to the top she had conditioned herself to fully accept a daughter who would find herself in such surroundings. “That sort of gift is at the heart of religion,” she told me. “To love your neighbor as yourself. To love that woman as I love Hannah.”

Barbara went to a number of religious services on the island, including at the Reformed church, at the Methodist church, and at the island’s only Jewish temple, built in 1833 by Spanish and Portuguese settlers. It is one of the oldest synagogues in the Western Hemisphere. Barbara started going to services every Sabbath, and described the synagogue as an “unlikely spiritual home in the wilderness.” The tile floor of the temple was covered in sand; according to legend, the sand symbolized the desert in which the Israelites wandered for forty years.

On a recent Sabbath, the rabbi, a transplant from Chevy Chase, Maryland, warmly welcomed Barbara. He had added Hannah’s name to the list of people whose recovery the congregation prayed for every week. By most counts, Hannah is one of five people still missing in the Virgin Islands in the wake of the storms. When the rabbi recited the prayer for healing, Barbara closed her eyes and bowed her head, remaining motionless long after it had ended. For much of the sermon, she gazed at the temple’s domed ceiling. The rabbi’s words were punctuated by frogs chirping outside the open door.

At the end of the service, we were all asked to stand in a circle and greet the person next to us. There were about twenty people there, most of them wearing shorts and sandals. Barbara introduced herself to a blond woman, a tourist, and explained why she was on the island. The woman said, automatically, “That’s terrible.”

After the service, Barbara and I went to dinner, and she seemed unusually deflated. “There’s a whole range of how people deal with the unknown,” she said. Hannah’s father told me in an e-mail, “I am sure that Hannah is alive . . . but I do not know IF she is ‘Safe in the Arms of Jesus’ or IF she is still walking around on this earth with the rest of us.”

When Barbara feels impatient for an answer, she reminds herself of a Quaker adage: “Live up to the light thou hast, and more will be granted thee.” The quest for her daughter—she described it as “navigating the realms of the watery unknown”—seemed to have also become a kind of end in itself. She and Hannah have always been close, but she felt she was accessing new facets of her daughter’s experience. “Sometimes, when I come to the end of the day, I just have to take some deep breaths, remember the things I heard, and be grateful for them and let them go,” she told me. “I have to realize that no matter how much I know about her, no matter how much more I learn, there’s still a mystery.”

Hannah’s two closest friends told me that they wondered if Barbara would stay on the island forever. She often described phases of her life using the word “journey,” and the search for her daughter had taken on a new dimension: she was connecting with the many lost women on the island who were not Hannah. “I need to be here, and I trust I’ll know when I need to be back home,” she told me. She felt that she was still piecing together clues and connections. She quoted a line from an Emily Dickinson poem, one of her favorites: “Not knowing when the dawn will come / I open every door.” ♦

This article appears in the print edition of the April 2, 2018, issue, with the headline “The Edge of Identity.”